Change 'rectilinear' to 'structured' in FAQ

[maxrjones]

Rectilinear is a very specific type of grid structure and I'm quite certain that VirtualiZarr can handle a broader set of grid types. I know people are already using Zarr for HEALPix and I think the virtual zarr approach has been demonstrated for curvilinear grids. I think 'structured' is a more appropriate description of the limitations of VirtualiZarr's approach.

[TomNicholas]

You're right to clarify this, but I think your clarification needs clarifying :D

I guess Zarr doesn't actually care about grids at all, only about multidimensional arrays. So we shouldn't even mention grids or grid-related words.

[maxrjones]

You're right to clarify this, but I think your clarification needs clarifying :D

I guess Zarr doesn't actually care about grids at all, only about multidimensional arrays. So we shouldn't even mention grids or grid-related words.

Yeah only the PR description mentions grids rather so I'm not sure more text adjustments would help. What do you think about adding a figure:

[TomNicholas]

I like the idea of a figure, but I find the layout of this particular image hard to parse. Perhaps we should brainstorm on this synchronously at a meeting.